The13-Lactam Antibiotics: Soon After the Introduction of Penicillin For Clinicaluse, It Was Recognised That Organism Could Develop Resistance to Penicillin.During the Irst Twenty Years Which Followed the Clinical Use of Penicillin,Development of New Compounds Based on the Penicillin Nucleus Took Place Slowly,But In the Twenty Years from 1 960 to 1 980 Many Different Types of Penicillinbecame Available. Yet the Organisms Developed Resistance To 13-Lactams By Different Mechanisms Such Asreduced Cell Permeability, Reduced Target Affinity, and Modification of Theantibiotic. of These the Modification of Antibiotic By P-Lactamase Productionis an Important Mechanism of Resistance Development (Georgopapadakou, 1993).